Nuclear data measurement and evaluations for nuclear power assay and waste management Paddy Regan, Department of Physics, University of Surrey & AIR Division, National Physical Laboratory p.regan@surrey.ac.uk paddy.regan@npl.co.uk Indo-UK Civil Nuclear Network Meeting Halifax Hall, Sheffield, 19 Dec. 2016

Aims, themes & focus for Indo-UK round IV? Emerging overall theme: ‘Enabling Technologies for Resilient Advanced Systems’ (i.e. safer, better power plants) Is there an opportunity for the UK nuclear physics research community to join Indo-UK Round IV ? Nuclear physics research / measurement community possible contribution? ‘Nuclear data – uncharted energies and isotopes’ (some helpful words from Bill Nuttall and Steven Ashley ).

What does the UK nuclear (physics) community do? NUclear STructure, Astrophysics & Reactions (NUSTAR = future project at FAIR facility, Germany, also includes current work at e.g., RIKEN (Japan), CERN-ISOLDE; FRIB (USA); Jyvaskyla (Finland); GANIL (France)…..) Spectroscopy and characterisation of nuclear energy levels and structure. Decay studies of radioactive species, superheavy elements, exotic nuclei... First Identification and characterisation of new/unusual (short-lived) isotopes. Reactions linked to nucleosynthesis e.g., neutron capture and a-clustering. Nucleon structure studies using EM probes of quark distributions. Nuclear matter at very high density/energy, searches for ‘quark gluon plasmas’. Applications of nuclear decay data Links to nuclear power, radiopharmaceuticals, waste assay (CTBT , (TE)NORMs). Construction of novel radiation detection system developments. Digital detection systems for high-resolution coincident spectroscopy. position-sensitive radiation measurements for radiation imaging. Funding Consolidated grant funding from the STFC (current round being ‘reviewed’). Limited Nuclear Data funding in the past from EPSRC (Manchester; Surrey; York). Strategy summarised in the 2016 UK ‘Nuclear Physics Advisory Group Roadmap’;

Physics driver example: Evolution of nuclear shell structure with changing proton (Z) and neutron (N) number. Excitation energy (keV) PHR, Physics World, Nov. 2011, p37 2+ 0+ Ground state Configuration. Spin/parity Ip=0+ ; Ex = 0 keV

2+ 0+ Excitation energy (keV) PHR, Physics World, Nov. 2011, p37 Ground state Configuration. Spin/parity Ip=0+ ; Ex = 0 keV

R(E(4+) / E(2+)) Systematics plot from Burcu Cakirli

A recently published example.

WAS3ABI & EURICA WAS3ABI: Wide-range Active Silicon-Strip Stopper Array for Beta and Ion detection Double-sided Silicon Strip Detectors 60 x 1 mm strips in x direction 40 x 1 mm strips in y direction EURICA: Euroball RIKEN Cluster Array for (ion correlated) gamma-ray measurements. 84 HPGe in 12 x 7 element CLUSTER dets. 18 LaBr3(Ce).

From the NPAG Road Map (2016) Report to STFC

Nuclear Data Nuclear data are nuclear physics parameters that allow modelling of nuclear systems in order to determine, for example: criticality shielding spent fuel inventory/activation decay heat as a function of time after irradiation antineutrino release/spectra Beta-delayed neutron emission for reactivity control. Basic nuclear parameters include: neutron reaction cross-sections reaction products and distribution in energy/angle decay data (half-lives, decay modes, emissions, …) fission yields energy per fission photon cross-sections Slide from UK Conference on Applied Radiation Metrology (CARM2015) 10-12 November 2015, National Physical Laboratory, Teddington, UK Courtesy: Alan L. Nichols

Nuclear Data (cont) Nuclear data and its evaluation underpin many areas of both applied and fundamental nuclear science, including: Nuclear (waste) fuel assay & fission fragment identification. Nuclear forensics (what fuel rod? Waste assay ? Isotope ratios?) Nuclear reactor operation / reaction (efficiency) modelling. Radioisotope production (relies on reaction cross-sections). Radiopharmaceutical applications and production) Fundamental studies of nuclear (structure) physics Input into International nuclear databases e.g., NEA / IAEA / JENDL/ NNDC, see e.g., http://www-nds.iaea.org/nsdd (IAEA-Vienna) https://www.oecd-nea.org/databank/ (OECD Paris)

What is nuclear data? Nuclear ground state masses, decay modes (a, b, fission,.) Nuclear decay lifetimes and partial decay modes Competing internal decays verses beta/alpha decay modes. b-delayed neutron probabilities (Pn(%)) values. Anti-neutrino and b- decay spectral shapes, average energies. Nuclear reaction cross-sections as a function of energy, (n,f), (a,n) reactions etc. thermal and fast neutron capture cross-sections. Reaction product distributions following fission. Excited state properties of nuclei. Characteristic gamma-ray energies & absolute Pg (%) values (e.g. 223Ra). Transition rates from nuclear excited states (lifetimes from ~10-15 s 1010 s). Internal conversion coefficients; Auger electron yields. Spins/parities of excited nuclear states ; gamma-ray decay multipolarities All of these needed for decay heat calculations.

Example from previous UK EPSRC Nuclear Data Grant?

Where do you find it, who looks after it? e.g., nndc http://www.nndc.bnl.gov/

e.g., 88Br decay

Complex energy-level scheme for 88Br (from NNDC data base)

Possible areas UK nuclear physics community could contribute to Indo-UK IV? Focus on measurement & evaluation of nuclear decay data. Specifically: Characteristic g-ray emissions from prompt and b-delayed fission fragments. Measurement/validation of fission fragment distributions for different fuels. Measurements of decay heat from fission fragments. Trans-uranic and Minor Actinide decay spectrometry Measurements of (new) b-delayed neutron-emission probabilities (BRIKEN). Measurements and evaluations of neutron capture cross-section (n-ToF). Some overlap with the recent STFC funded UK Nuclear Data Network and recent (small) nuclear data projects at NPL partially funded by the UK Nuclear Measurement Office. Potential role of the NPL Neutron facility for fast-neutron induced cross-section measurements Provision of reference materials for nuclear waste assay calibration Non-proliferation by nuclear forensic measurements (isotope ratios); CTBT

Examples of recent instrument development. i. e Examples of recent instrument development. i.e. How you get new, up to date ‘nuclear data’

The Future: FATIMA for DESPEC FATIMA = FAst TIMing Array = State of the art gamma-ray detection array for precision measurements of nuclear structure in the most exotic and rare nuclei. Part of the ~ £8M STFC NUSTAR project grant (runs 2012-16). Good energy resolution (better than 3% at 1 MeV). Good detection efficiency (between than 5% Full-energy peak at 1 MeV). Excellent timing qualities (approaching 100 picoseconds). Use to measure lifetimes of excited nuclear states & provide precision tests of theories of nuclear structure, uses a fully-digitised Data Acquisition System. Collaboration with NPL (Radioactivity group) through NMO project on ‘Nuclear Data’ (Judge, Jerome, Regan et al.,) on parallel development of NPL-based array for use in traceable radioactive standards and traceability to the Bq.

Some existing links between UK and Indian nuclear structure physics reseach groups? Main current area of overlap is via gamma-ray spectroscopy of exotic nuclei using high-resolution arrays. Collaborative work at GSI (and later FAIR) on decay spectroscopy with UK groups and VECC (Kolkata); TIFR (Mumbai); New Delhi/ IIT Roorkee. These groups perform experiments at their home institutes in India using e.g., the INGA gamma-ray spectrometer. They are also involved (formal partner) in the FAIR NUSTAR project for spectroscopic studies of heavy, neutron-rich nuclei (e.g., fission fragments).

UK Nuclear Data Network

Some current STFC UK NDN case studies (2017-2020) 13C(n,g) cross-section measurements (Manchester / York) Needed for better estimates of legacy waste via creation of 14C in nuclear power plants. Prompt-neutron induced fission of 238U (Surrey / NPL / York ) At the IPN-ORSAY/ALTO facility, Paris with the LICORNE neutron facility using the NuBALL gamma-ray array for in-beam and decay spectroscopy of neutron-rich fission fragments. Investigations of ‘isomer delayed’ decay heat. Beta-delayed neutron emission probabilities (NPL / Surrey / York /…) At BRIKEN (RIBF- Japan); Will measure and validate Pn(%) values in the shortest-lived (T1/2 <1 s) fission residues to evaluate better additional neutron production from decay of fission fragments in reactor cores. STEFF at n-TOF (Manchester/ York/ …) Measures neutron-induced fission mass distributions, total prompt gamma-ray energies and gamma-ray multiplicities).

Role of National Physical Laboratory (NPL)? Validation and creation of reference materials for radiation measurements and instrument calibration (e.g., on site validations ; 236Np ; (actinide) radiochemistry expertise). Development of the ‘mobile laboratory’ for radionuclide assay and checks ‘on site’. Application of unique UK tunable fast-neutron facility (~1 – 10 MeV) for cross-section measurements. Leading some nuclear data measurements via UKNDN at e.g., BRIKEN for Pn values and mass measurements. High accuracy measurements of long-lived radioisotope half-lives (e.g. 238U 4.5x109 years; 244Pu ; 237Np etc). Needed for public ‘confidence’ in waste assay. Provide (with U. Surrey) ‘world class’ training in radionuclide metrology and measurement.

Standardisation of 223Ra High-impact joint Surrey-NPL publication on Radium-223. Sean Collins is a 2nd year part-time student on the MSc in Radiation and Environmental Protection at Surrey, while also a full-time research scientist at NPL.

Thank you.

UKNDN Details ? e.g. 238U prompt-neutron fission? Use a highly-selective, hybrid gamma-ray spectrometer combining LaBr3 scintillation detectors together with HPGe detectors at the Institute of Nuclear Physics (IPN) Orsay, France for precision spectroscopic studies of decays of neutron-rich fission fragment residues. The study will focus on gamma-ray emission following fast neutron-induced fission using the LICORNE directional neutron source. This will provide both nuclear structure information on the fission fragments produced and additional information on the excitation energy distribution of the prompt fission fragments in fast-neutron induced fission. These data will provide information on prompt gamma heat in potential Gen IV / fast-neutron nuclear reactors.

Beta-delayed neutron-emission probabilities. Beta-delayed neutron emission is necessary for control of a thermal reactor. This project aims to contribute to the accurate evaluation and measurement of beta-delayed neutron decay probabilities (Pn values) in a wide range of neutron-rich nuclei. These will be created artificially in state of the art nuclear science laboratories in Japan (RIBF) and Europe (FAIR & JYFL). The data obtained in this project will provide important checks on existing nuclear data on beta-delayed neutron emissions and, it is hoped, provide the first data on a number of neutron-rich nuclides which have not been able to be (accurately) studied before.